A navigation system performs travel guidance for enabling a user to easily and quickly reach the selected destination. A typical example is a vehicle navigation system where a user drives a car equipped with a navigation function. Such a navigation system detects the position of the user or user's vehicle, and reads out map data pertaining to an area at the current vehicle position from a data storage medium, for example, a CD-ROM (compact disc read-only memory), a DVD (digital versatile disc), or a hard disc. Alternatively, such map data can be provided to the user from a remote server through a communication network such as Internet. The navigation system displays a map image on a monitor screen while superimposing a mark representing the current location of the user on the map image.
When a destination is set, the navigation system starts a route guidance function for setting a guided route from the start point to the destination. To determine the guided route to the destination, the navigation system calculates and determines an optimum route to the destination based on various parameters. For example, the guided route is determined based on the shortest way to reach the destination, the route preferring freeways to surface roads, the least expensive way to the destination, the route without using toll road, or the like.
During the route guidance, the navigation system reads the nodes data from the data storage medium such as DVD and successively stores the nodes data of road segments (expressed in longitude and latitude) constituting the guided route in a map memory. In the actual traveling, the node series stored in the map memory is searched for a portion of the guided route to be displayed in a map display area of the monitor screen, and the portion of the guided route is highlighted to be clearly distinguished from other routes. When the vehicle is within a predetermined distance of an intersection it is approaching, an intersection guidance diagram (an enlarged or highlighted intersection diagram with an arrow indicating the direction in which the vehicle is to turn at the intersection) is displayed to inform a user of the desired one of roads or directions selectable at the intersection. Such route guidance by the navigation system is also given by voice instruction.
FIGS. 1A-1H show an example of overall procedure and screen display involved in the navigation system. FIG. 1A shows an example of locator map screen of the navigation system when the destination is not specified. Typically, the navigation system displays a street on which the vehicle (current vehicle position VP) is running on a map image and a name of the street. Other information such as a north pointer NP, a map scale and a current time may also be illustrated on the display screen.
An example of process for specifying a destination in the navigation system through a Point of Interest (POI) search method is shown in FIG. 1B-1F. A main menu screen such as shown in FIG. 1B displays menu items including a “Destination” menu for entering the destination. When selecting “Destination”, the navigation system displays an “Find Destination by” screen as shown in FIG. 1C for specifying an input method for selecting the destination. The “Find Destination By” screen lists various methods for selecting the destination including “Address” for specifying the city and address of the destination, “Intersection” for specifying the names of two streets which intersect with one another, and “Point of Interest (POI)” for selecting the programmed destination based on the name, category or telephone number. Other methods in the “Find Destination by” screen include “Recent Route” for specifying the destination based on the recent history of destinations saved in the navigation system, and “Address Book” for selecting the address of the destination out of the prescribed address list stored in the system.
When selecting, the “Point of Interest” method in FIG. 1C, the navigation system displays selection methods of point of interest (POI) either by “Place Name” or “Place Type” in FIG. 1D. The “Place Name” is to specify a name of POI, and the “Place Type” is to specify a category of POI. If the “Place Type” is selected in FIG. 1D, the navigation system lists categories of POIs as shown in FIG. 1E. The order of listing the categories may be arranged in, for example, an alphabetical order or an order of distance from the current position. The user selects a desired category of POIs from the lists. If there are many entries in the list that cannot be displayed on one screen, a user may scroll the list by a scroll key of a scroll bar.
FIG. 1F shows a screen when the user has selected a “Fast Foods” category in the example of FIG. 1E. In this example, the screen includes the name of POI type “Fast Foods” at the top and a list of names of the fast food restaurants typically sorted by distance from the current destination. The list may also show rough direction of each fast food restaurant by an arrow. In this example, the user selects “Pizza Hut” as his destination.
In FIG. 1G, the navigation system calculates and determines a guided route to the destination, i.e., the selected POI “Pizza Hut”. In this example, the navigation system displays a progress scale during the calculation of the route to the destination. After determining the guided route, the navigation system starts the route guidance as shown in FIG. 1H. Typically, the navigation system shows the intersection which is highlighted to show the next turn and a direction of the turn. Such route guidance by the navigation system is also given by voice instruction.
POIs are sometimes located within a large structure or a large compound (hereafter “large structure”). For example, rather than on a side of a street, a restaurant may be located in a shopping mall, an airport, train station, an amusement park, or the like. Sometimes, a user wants to find a particular POI, such as a restaurant, not because he wants to eat there but rather wants to go to the large structure where the particular restaurant is located. For example, he wants to meet someone in the compound or wants to use a rest room, etc. Moreover, the user sometimes wants to know whether the specific POI is located within a large structure or not. For example, the user may want to avoid a restaurant in a large shopping mall because the restaurant can be far away from the parking lot. In a case where a restaurant is located inside an airport, or other large compound, the user may have to pay a parking fee.
FIGS. 2A-2B show map images involving such situations where a POI is located within a large structure or is located independently from a large structure. A solid circle on the map indicates the position of a specific POI “Pizza Hut”. The situation of FIG. 2A indicates that “Pizza Hut” is located independently. In FIG. 2B, the shaded area indicates a large structure such as a shopping mall, airport, or train station, etc. In this example, “Pizza Hut” is located within the large structure.
In the conventional display method of FIG. 3A which shows a list of POIs, the user cannot tell whether a particular POI is located within a large structure. The screen merely shows a list of POIs, distances to the POIs, and rough directions to that POIS. In the conventional display method, it would be possible to additionally include information as to whether a particular POI is associated with a large structure. Such an example is shown in FIG. 3B where a name of large structure is added to the POI in the POI name list. For instance, a POI “Burger King” is accompanied by “LAX Airport” as a large structure to show that “Burger King” is located within the Los Angeles Airport. Likewise, the display shows that “Kentucky Fried Chicken” is located within a shopping mall “Fairground Mall”, and “Pizza Hut” is located within “LA Station”.
However, this type of display is not appropriate for a vehicle navigation system. First, because the navigation system is mainly used in a limited space such as within an automobile, the space allowed for the navigation display is likewise limited. It is difficult to provide information on both POI and large structure on the display. Second, too much information on each entry tends to distract the user's attention to the safe driving. To minimize text information is desired in order not to distract the user's attention for safe driving. Thus, there is a need for a navigation system that can effectively inform the user whether a particular POI is located in a large structure or not.